Android tests call exit() when complete.

[ Merge of http://go/wvgerrit/119804 ]

The coverage framework used by Android requires the process to call
exit() for coverage information to be dumped after the tests.

Android unit tests have been adapted to use the a new main module.
The core test_main.cpp used by integration tests has been updated to
call exit().

Bug: 138941105
Test: Linux and Android unittests
Change-Id: Ifffc7b8290c50dffe527738a36547c1d2fb90bd3

libwvdrmengine/cdm/test/cdm_test_main.cpp

@@ -0,0 +1,17 @@
+// Copyright 2021 Google LLC. All Rights Reserved. This file and proprietary
+// source code may only be used and distributed under the Widevine License
+// Agreement.
+#include <stdlib.h>
+
+#include "gtest/gtest.h"
+
+#include "log.h"
+
+int main(int argc, char** argv) {
+  LOGI("Running Android CDM tests");
+  testing::InitGoogleTest(&argc, argv);
+  const int status = RUN_ALL_TESTS();
+  LOGD("CDM test complete with status %d", status);
+  exit(status);  // Explicit call to exit() is required for code coverage.
+  return status;
+}

libwvdrmengine/cdm/test/unit-test.mk

@@ -20,6 +20,7 @@ LOCAL_SRC_FILES := \
     ../core/test/url_request.cpp \
     ../../oemcrypto/test/oec_device_features.cpp \
     ../util/test/test_sleep.cpp \
+    ./cdm_test_main.cpp \
 
 LOCAL_C_INCLUDES := \
     vendor/widevine/libwvdrmengine/android/cdm/test \
@@ -44,7 +45,6 @@ LOCAL_STATIC_LIBRARIES := \
     libjsmn \
     libgmock \
     libgtest \
-    libgtest_main \
     libwvlevel3 \
 
 LOCAL_SHARED_LIBRARIES := \